Process for the preparation of phosphinic acid esters

ABSTRACT

The invention relates to a process for the preparation of alkyl phosphinates, alkenyl phosphinates, alkynyl phosphinates or phenyl phosphinates by reaction of a corresponding phosphine oxide with an alcohol or phenol in the presence of alkali-metal fluoride or tetraalkylammonium fluoride.

The invention relates to a process for the preparation of alkyl phosphinates, alkenyl phosphinates, alkynyl phosphinates or phenyl phosphinates by reaction of a corresponding phosphine oxide with an alcohol or phenol in the presence of alkali-metal fluoride or tetraalkylammonium fluoride.

Alkyl esters of bis(alkyl)phosphinic acids are known flameproofing agents and assistants for the reduction of viscosities. The alkylating power of the alkyl bis(alkyl)phosphinates can be increased by exchange of the alkyl group by partially fluorinated alkyl groups or perfluorinated alkyl group. The methyl ester of bis(heptafluoropropyl)phosphinic acid is, according to N. V. Pavlenko et al, J. Gen. Chem. USSR (Engl. Transl.), 59, 3, 1989, 474-476, capable of methylating the weak base 2-trifluoromethylbenzothiazole quantitatively at 20° C.

The methyl ester of bis(pentafluoroethyl)phosphinic acid is, according to N. V. Ignat'ev, J. Fluorine Chem., 130, 2009, 1183-1191, capable of methylating the chloride or bromide of an organic salt with chloride or bromide anion. Organic salts with bis(pentafluoroethyl)phosphinate anions also form in this alkylation reaction.

The methyl ester of bis(trifluoromethyl)phosphinic acid can be prepared, for example, by alkylation of mercury bis(trifluoromethyl)phosphinate using methyl iodide (A. B. Burg et al, Inorg. Chem., 8, 5, 1969, 1199-1201). Alkyl esters of bis(heptafluoropropyl)phosphinic acid can be prepared, for example, by reaction of silver bis(heptafluoropropyl)phosphinate with alkyl iodides (N. V. Pavlenko et al, J. Gen. Chem. USSR (Engl. Transl), 59, 3, 1989, 474-476).

Alkyl esters of bis(perfluoroalkyl)phosphinic acids can also be prepared by alcoholysis of bis(perfluoroalkyl)phosphinyl chlorides in the presence of an organic base, for example in the presence of trimethylamine (R. G. Cavell et al, Inorg. Chem., 18, 10, 1979, 2901-2908). However, the alcoholysis does not succeed in satisfactory yield with methanol.

Even without the presence of base, the methanolysis of bis(perfluoroalkyl)-phosphinyl chloride is not satisfactory. N. V. Pavlenko et al, J. Gen. Chem. USSR (Engl. Transl), 59, 3, 1989, 474-476 postulates that the methyl ester formed as an intermediate reacts with methanol to form the dimethyl ether, and bis(perfluoroalkyl)phosphinic acid forms.

Alkyl esters of bis(perfluoroalkyl)phosphinic acids can also be prepared by reaction of perfluoroalkyl iodides with alkyl phosphates, (alkylO)₃P═O, at temperatures of 60° C. in the presence of zinc/copper and subsequent acidic hydrolysis (S. Benefice-Malouet et al, J. Fluorine Chem., 30, 1985, 171-188).

Patent US 2003-189193 describes a process for the preparation of methyl esters of bis(perfluoroalkyl)phosphinic acids by conversion of perfluoroalkyl iodides into Grignard reagents (R_(F)MgBr) at temperatures below −45° C. and reaction thereof with POCl₃ and subsequent reaction with methanol.

There is still a need to prepare this interesting class of alkylating agents in an alternative way to conventional methods.

The object of the invention is therefore to develop an alternative or improved process for the preparation of alkyl esters of phosphinic acids which meets the demands of an industrial-scale economical synthesis.

It is known to date that tris(perfluoroalkyl)phosphine oxides form complexes with alcohols (V. Ya. Semenii et al, Zh. Obshchei Khim. (Russ), 48, 6, 1978, 1325-1331). Complexes of this type decompose on warming above 40° C. and form various decomposition products. Isolation of alkyl esters of a bis(perfluoroalkyl)phosphinic acid is not described. Rapid reaction of the alkyl esters in the presence of alcohol with formation of bis(perfluoroalkyl)-phosphinic acid is also assumed here.

A similar result has also been observed by N. V. Pavlenko et al, J. Gen. Chem. USSR (Engl. Transl.), 59, 3, 1989, 474-476. In the case of the reaction of bis(heptafluoropropyl)phosphine oxide with methanol, only bis(heptafluoropropyl)phosphinic acid and dimethyl ether were isolated.

Surprisingly, it has been found that the addition of an alkali-metal fluoride or tetraalkylammonium fluoride enables isolation of the desired alkyl esters, which were hitherto merely postulated as intermediates. The alkyl groups of the tetraalkylammonium fluoride are in each case, independently of one another, a straight-chain or branched alkyl group having 1 to 10 C atoms.

Accordingly, the invention relates firstly to a process for the preparation of phosphinic acid esters of the formula (I) (C_(n)F_(2n+1−y)H_(y))₂P(O)OR  (I), where n in each case, independently of one another, denotes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, y in each case, independently of one another, denotes 0, 1, 2, 3 or 4, R denotes unsubstituted or substituted phenyl, a straight-chain or branched, unfluorinated or partially fluorinated or deuterated alkyl group having 1 to 30 C atoms or a straight-chain or branched, unfluorinated or partially fluorinated alkenyl or alkynyl group having 3 to 30 C atoms, where R may be partially substituted by halogen and/or partially substituted by —OH, —C(O)OH, N(CH₃)₂ and —CN and where one or two carbon atoms of the alkyl, alkenyl or alkynyl group which are not adjacent and are not in the α-position to the oxygen atom or to carbon atoms of the double bond or triple bond may be replaced by atoms and/or atom groups selected from the group —O—, —S—, —S(O)—, —SO₂—, —C(O)—, —C(O)O— or —N(R′)— and R′ in each case, independently of one another, denotes H, a straight-chain or branched, unfluorinated or partially fluorinated alkyl group having 1 to 18 C atoms, saturated C₃- to C₇-cycloalkyl, unsubstituted or substituted phenyl, by reaction of a phosphine oxide of the formula (II) (C_(n)F_(2n+1−y)H_(y))₃P(O)  (II), where n and y have a meanings indicated in the case of the formula (I), with an alcohol or phenol R—OH in the presence of alkali-metal fluoride or tetraalkylammonium fluoride, where R has a meaning indicated in the case of the formula (I), where the water content in this reaction is in total a maximum of 1000 ppm and where alkyl in tetraalkylammonium in each case, independently of one another, denotes a straight-chain or branched alkyl group having 1 to 10 C atoms.

The starting compounds, i.e. the phosphine oxides of the formula (II), alcohols or phenols ROH, alkali-metal fluorides and/or tetraalkylammonium fluorides named, are commercially available or can be prepared by known methods.

The phosphine oxides of the formula (II) can be prepared, for example, by reaction of tris(fluoroalkyl)difluorophosphoranes or tris(perfluoroalkyl)-difluorophosphoranes with alkaline-earth metal oxides, alkaline-earth metal carbonates, zinc oxide, copper(I) oxide, copper(II) oxide, silver oxide, mercury(II) oxide, cadmium oxide or cadmium carbonate, as described in WO 2011/110281. The preparation of the starting compounds tris(perfluoroalkyl)difluorophosphorane can be prepared, for example, by electrochemical fluorination of suitable starting compounds, as described in V. Ya. Semenii et al, Zh. Obshch. Khim., 55, 12, 1985, 2716-2720, N. Ignatiev et al, J. of Fluorine Chem., 103, 2000, 57-61 and WO 00/21969. The corresponding descriptions are hereby incorporated by way of reference and are regarded as part of the disclosure.

The reaction according to the invention is particularly preferably carried out with exclusion of water, where the water content is in total a maximum of 1000 ppm. The water content is very particularly preferably in total 10 to 200 ppm.

The alcohol or phenol ROH is preferably employed with a residual water content between 10 to 1000 ppm, particularly preferably with a residual water content between 10 and 200 ppm.

The alkali-metal fluoride or tetraalkylammonium fluoride is preferably employed with a residual water content between 0 to 990 ppm, particularly preferably with a residual water content between 0 and 190 ppm.

In accordance with the invention, the alkali-metal fluorides from the group lithium fluoride, sodium fluoride, potassium fluoride, rubidium fluoride or caesium fluoride can be employed or tetraalkylammonium fluorides in which the alkyl group in each case, independently of one another, denotes a straight-chain or linear alkyl group having 1 to 10 C atoms.

A straight-chain or branched alkyl group having 1 to 10 C atoms is, for example, methyl, ethyl, isopropyl, propyl, butyl, sec-butyl or tert-butyl, pentyl, 1-, 2- or 3-methylbutyl, 1,1-, 1,2- or 2,2-dimethylpropyl, 1-ethyl-propyl, n-hexyl, n-heptyl, n-octyl, n-nonyl or n-decyl.

Preferred tetraalkylammonium fluorides are salts in which all alkyl groups are identical, for example tetramethylammonium fluoride or tetra(n-butyl)-ammonium fluoride.

In accordance with the invention, the fluorides potassium fluoride, sodium fluoride, rubidium fluoride, caesium fluoride or tetramethylammonium fluoride are preferably employed. Potassium fluoride is very particularly preferably employed.

The amount of the above-described alkali-metal fluoride or tetraalkylammonium fluoride employed is preferably between 0.05 and 0.5 mol based on 1 mol of phosphine oxide of the formula (II), very particularly preferably 0.1 mol based on 1 mol of phosphine oxide of the formula (II).

The solids employed in the process according to the invention should preferably be employed in the ground (spray-dried) state in order that the largest possible surface area is present for the reaction.

Any type of grinding is possible, for example grinding by means of a ball mill.

In the process according to the invention, the alcohol or phenol ROH can, as described above or below, be employed with an excess up to 10%, compared with the amount of the phosphine oxide of the formula (II) employed, as described in detail above or below. The two compounds are preferably employed in equimolar amount.

In a preferred embodiment of the process, the alkali-metal fluoride or tetraalkylammonium fluoride is added to the phosphine oxide of the formula (II) at temperatures of −10° C. to 0° C., the alcohol or phenol is added, and the reaction mixture is subsequently warmed to a temperature of 20° C. to 60° C. until the reaction is complete.

In a particularly preferred embodiment of the process, the alkali-metal fluoride or tetraalkylammonium fluoride is added to the phosphine oxide of the formula (II) at 0° C., the mixture is optionally stirred at this temperature for one hour, the alcohol or phenol is then added, and the reaction mixture is warmed at a temperature of 25° C. until the reaction is complete.

The reaction can be carried out in a glass apparatus or in an apparatus made from plastic (such as, for example, Teflon) or steel.

Working without solvents is preferred. However, it is also possible to work in the presence of solvents which are inert to the compounds of the formula (I) and (II) and to alkali-metal fluorides or tetraalkylammonium fluorides, for example acetonitrile, propionitrile, hexane or 1,2-dimethoxyethane.

Preference is given to the preparation of compounds of the formula (I), as described above, in which the variable y denotes 0, 1 or 2, particularly preferably in which the variable y denotes 0.

Accordingly, preference is given to starting materials of the formula (II) in which the variable y denotes 0, 1 or 2, particularly preferably the starting materials of the formula (II) are preferred in which the variable y denotes 0.

Preference is given to the preparation of compounds of the formula (I), as described above, in which the variable n denotes 1, 2, 3 or 4, particularly preferably in which the variable n denotes 2, 3 or 4.

In the compounds of the formula (I) or in the alcohol or phenol ROH, R denotes unsubstituted or substituted phenyl, a straight-chain or branched, unfluorinated or partially fluorinated or deuterated alkyl group having 1 to 30 C atoms or a straight-chain or branched, unfluorinated or partially fluorinated alkenyl or alkynyl group having 3 to 30 C atoms, where R may be partially substituted by halogen and/or partially substituted by —OH, —C(O)OH, N(CH₃)₂ and —CN and where one or two carbon atoms of the alkyl, alkenyl or alkynyl group which are not adjacent and are not in the α-position to the oxygen atom or to carbon atoms of the double bond or triple bond may be replaced by atoms and/or atom groups selected from the group —O—, —S—, —S(O)—, —SO₂—, —C(O)—, —C(O)O— or —N(R′)— and

R′ in each case, independently of one another, denotes H, a straight-chain or branched, unfluorinated or partially fluorinated alkyl group having 1 to 18 C atoms, saturated C₃- to C₇-cycloalkyl, unsubstituted or substituted phenyl.

A straight-chain or branched alkyl group having 1 to 30 C atoms encompasses the group described above of straight-chain or branched alkyl group having 1 to 10 C atoms and undecanyl, dodecanyl, tridecanyl, tetradecanyl, pentadecanyl, hexadecanyl, heptadecanyl, octadecanyl, nonadecanyl, eicosanyl, heneicosanyl, docosanyl, tricosanyl, tetracosanyl, pentacosanyl, hexacosanyl, heptacosanyl, octacosanyl, nonacosanyl and triacontanyl.

A straight-chain or branched alkenyl or alkynyl having 3 to 30 C atoms, where a plurality of double or triple bonds may also be present, is, for example, allyl, 2- or 3-butenyl, isobutenyl, sec-butenyl, furthermore 4-pentenyl, isopentenyl, hexenyl, heptenyl, octenyl, —C₉H₁₇, —C₁₀H₁₉ to —C₃₀H₄₉, propargyl, 2- or 3-butynyl, C₅H₇ to C₃₀H₄₇, preferably allyl, 2- or 3-butenyl, isobutenyl, sec-butenyl, 4-pentenyl, isopentenyl, hexenyl or decenyl or propargyl.

Partially fluorinated means that at least one H atom of the corresponding alkyl, alkenyl or alkynyl group has been replaced by an F atom. Perfluorinated means that all H atoms of the corresponding alkyl or alkenyl or alkynyl group have been replaced by F atoms. Deuterated means that at least one H atom of the corresponding alkyl, alkenyl or alkynyl group has been replaced by a deuterium atom.

Examples of a straight-chain or branched alkyl group having 2 to 10 C atoms, which may be partially substituted by halogen and/or partially substituted by —OH, —C(O)OH, N(CH₃)₂ and —CN and where one or two carbon atoms which are not adjacent and are not in the α-position to the oxygen atom or to carbon atoms of the double bond or triple bond may be replaced by atoms and/or atom groups selected from the group —O—, —S—, —S(O)—, —SO₂—, —C(O)—, —C(O)O— or —N(R′)—, are —CH₂—O—CH₃, —CH₂—CH₂—O—CH₃, —CH₂—CH₂—O—CH₂—CH₃, —CH₂—C(O)OH, —CH₂—CH₂—NH—CH₃, —CH₂—N(CH₃)₂, —CH₂—CH₂—N(CH₃)₂, —CH₂—S—CH₃, —CH₂—CH₂—S—CH₃, —CH₂—CH₂—S—CH₂—CH₃, —CH₂—CH₂—S(O)₂OH, —CH₂—CH₂—CH₂—S(O)₂OH, —CH₂—CH₂—CH₂—CH₂—S(O)₂OH, —CH₂—CH₂—O—CH₂—CH₂—O—CH₃, —CH₂—CH₂—O—CH₂—CH₂—S—CH₃, —CH₂—CH₂—O—CH₂—CH₂—O—CH₂—CH₂—O—CH₃, —CH₂—CH₂—S(O)—CH₃, —CH₂—CH₂—SO₂—CH₃, —CH₂—CH₂—C(O)—CH₃, —CH₂—CH₂—C(O)O—CH₃, —CH(CH₃)—C(O)OH, —CH₂—CH₂—CH₂—C(O)OH, —(CH₂)₉—C(O)O—CH₃, —CH₂—CH₂—O—CH₂—CH₂—O—CH₂—CH₂—C(O)O—CH₂—CH₂—CH₃, —CH₂—CH₂—CH₂—Br, —CH₂—CH₂—O—CH₂CF₃, —CH₂—CH₂—CH₂—OH or —CH₂—CH₂—CN.

Examples of a straight-chain or branched partially fluorinated alkyl group having 3 to 10 C atoms, where one or two carbon atoms which are not adjacent and are not in the α-position to the oxygen atom may be replaced by atoms and/or atom groups selected from the group —O—, —S—, —S(O)—, —SO₂—, —C(O)—, —C(O)O— or —N(R′)—, are —CH₂—CH₂—O—CF₃, —CH₂—CH₂—O—CH₂—CF₃, —CH₂— (CF₂)₃— CF₂H, —CH₂—CH₂—N(CF₃)₂, —CH₂—CH₂—S—CF₃, —CH₂—CH₂—S—CH₂—CF₃, —CH₂—CH₂—O—CF₂—CF₂—O—CH₃, —CH₂—CH₂—S(O)—CF₃, —CH₂—CH₂—SO₂—CF₃, —CH₂—CH₂—C(O)—CH₂—CF₃, —CH₂—CH₂—C(O)O—CH₂—CF₃ or —CH₂—CH₂—(CF₂)₂—C(O)O—CH₃.

Examples of a straight-chain or branched alkenyl group having 3 to 10 C atoms, where one or two carbon atoms which are not adjacent and are not in the α-position to the oxygen atom may be replaced by atoms and/or atom groups selected from the group —O—, —S—, —S(O)—, —SO₂—, —C(O)—, —C(O)O— or —N(R′)—, are —CH₂—O—CH═CH₂, —CH₂—S—CH═CH₂, —CH₂—NH—CH═CH₂, —CH₂—N(CH₃)—CH₂—CH═CH₂, —CH₂—CH₂—O—CH₂—CH═CH₂, —CH₂—CH₂—O—CH═CH₂, —CH₂—CH₂—S—CH₂—CH═CH₂, —CH₂—CH₂—C(O)—CH₂—CH═CH₂, —CH₂—CH₂—C(O)—CH═CH₂, —CH₂—CH₂—C(O)O—CH₂—CH═CH₂, —CH₂—CH₂—S(O)—CH₂—CH═CH₂, —CH₂—CH₂—SO₂—CH₂—CH═CH₂, —CH₂—(CH₂)₂—O—CH₂—CH═CH₂, —CH₂—(CH₂)₃—O—CH₂—CH═CH₂, —CH₂—(CH₂)₄—O—CH₂—CH═CH₂, —CH₂—(CH₂)₅—O—CH₂—CH═CH₂ or —CH₂—(CH₂)₆—O—CH₂—CH═CH₂.

Examples of a straight-chain or branched alkynyl group having 3 to 10 C atoms, where one or two carbon atoms which are not adjacent and are not in the α-position to the oxygen atom may be replaced by atoms and/or atom groups selected from the group —O—, —S—, —S(O)—, —SO₂—, —C(O)—, —C(O)O— or —N(R′)—, are —CH₂—N(CH₃)—CH₂—C≡CH, —CH₂—CH₂—O—CH₂—C≡CH, —CH₂—CH₂—S—CH₂—C≡CH, —CH₂—CH₂—C(O)—CH₂—C≡CH, —CH₂—CH₂—C(O)—C≡CH, —CH₂—CH₂—C(O)O—CH₂—C≡CH, —CH₂—CH₂—S(O)—CH₂—C≡CH, —CH₂—CH₂—SO₂—CH₂—C≡CH, —CH₂—(CH₂)₂—O—CH₂—C≡CH, —CH₂—(CH₂)₃—O—CH₂—C≡CH, —CH₂—(CH₂)₄—O—CH₂—C≡CH, —CH₂—(CH₂)₅—O—CH₂—C≡CH or —CH₂—(CH₂)₆—O—CH₂—C≡CH.

Examples of a saturated C₃- to C₇-cycloalkyl are cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or cycloheptyl.

Substituted phenyl in R′ or R denotes a phenyl group, which may be substituted by a straight-chain or branched, unfluorinated, partially fluorinated or perfluorinated alkyl group having 1 to 6 C atoms, a straight-chain or branched, unfluorinated, partially fluorinated or perfluorinated alkenyl group having 2 to 10 C atoms, a straight-chain or branched, unfluorinated, partially fluorinated or perfluorinated alkynyl group having 2 to 10 C atoms, —CN, —NO₂, F, Cl, Br, I, —OH, a straight-chain or branched, unfluorinated, partially fluorinated or perfluorinated alkoxy group having 1 to 6 C atoms, N(R″)₂, —COOH, —C(O)OR″, —C(O)R″, —SO₂X′, —SR″, —S(O)R″, —SO₂R″, SO₂N(R″)₂ or SO₃H, where X′ denotes F, Cl or Br and R″ denotes an unfluorinated, partially fluorinated or perfluorinated straight-chain or branched alkyl group having 1 to 6 C atoms, for example o-, m- or p-methylphenyl, o-, m- or p-ethylphenyl, o-, m- or p-propylphenyl, o-, m- or p-isopropylphenyl, o-, m- or p-tert-butylphenyl, o-, m- or p-nitrophenyl, o-, m- or p-hydroxy-phenyl, o-, m- or p-methoxyphenyl, o-, m- or p-ethoxyphenyl, o-, m- or p-(trifluoromethyl)phenyl, o-, m- or p-(trifluoromethoxy)phenyl, o-, m- or p-(trifluoromethylsulfonyl)phenyl, o-, m- or p-fluorophenyl, o-, m- or p-chloro-phenyl, o-, m- or p-bromophenyl, o-, m- or p-iodophenyl.

Preference is given to the preparation of compounds of the formula (I) in which R denotes a straight-chain or branched unfluorinated or partially fluorinated alkyl group having 1 to 10 C atoms, a straight-chain or branched alkenyl group having 3 to 10 C atoms, a straight-chain or branched alkynyl group having 3 to 10 C atoms or unsubstituted or substituted phenyl, where one or two carbon atoms which are not adjacent and are not in the α-position to the oxygen atom or to carbon atoms of the double bond or triple bond may be replaced by atoms and/or atom groups selected from the group —O—, —C(O)— or C(O)O—.

Particular preference is given to the preparation of compounds of the formula (I) in which R denotes a straight-chain or branched unfluorinated or partially fluorinated alkyl group having 1 to 4 C atoms, a straight-chain or branched alkenyl group having 3 to 10 C atoms, a straight-chain alkynyl group having 3 to 6 C atoms or phenyl, where a carbon atom which is not adjacent and is not in the α-position to the oxygen atom or to carbon atoms of the double bond or triple bond may be replaced by —O—.

Very particular preference is given to the preparation of compounds of the formula (I) in which R denotes methyl, ethyl, 2,2,2-trifluoroethoxyethyl, 3-bromopropyl, 3-hydroxypropyl, 2-cyanoethyl, 2,2,3,3,4,4,5,5-octafluoropentyl, allyloxyethyl, allyl, decenyl, propargyl or phenyl.

The compounds of the formula (I) prepared by the process according to the invention, as described above, are pure compounds and are ideally suitable for the further reaction, in particular for the alkylation of organic compounds, but in particular for the preparation of organic salts with the phosphinate anion corresponding to the phosphinic acid ester. The following examples also show, inter alia, this application.

The compounds of the formula (I) may also be prepared in deuterated form in accordance with the invention by starting from deuterated alcohols or phenols and reacting correspondingly to the process according to the invention.

Even without further comments, it is assumed that a person skilled in the art will be able to utilise the above description in the broadest scope. The preferred embodiments and examples should therefore merely be regarded as descriptive disclosure which is absolutely not limiting in any way.

EXAMPLES

NMR spectroscopy: NMR samples are measured either in a 5 mm (Ø_(A)) glass NMR tube or in a 3.7 mm (Ø_(A)) FEP inliner at 25° C. In the case of measurements in FEP, the inliner is introduced into a 5 mm (Ø_(A)) precision glass NMR tube (Wilmad 537). The locking agent (CD₃CN) is thus located in the glass NMR tube between glass and FEP inliner. The measurements are carried out on a 400 MHz Bruker Avance III spectrometer with a 9.3980 T cryomagnet and a 5 mm BBFO sample head.

¹H NMR spectra are measured in a ¹H/¹⁹F channel at 400.17 MHz. ¹³C, ¹⁹F and ³¹P NMR spectra were measured in a broadband channel at 100.62, 376.54 and 161.99 MHz. The ¹H NMR chemical shifts are relative to tetramethylsilane (TMS) and arise for the solvents CDCl₃ (7.24 ppm) and CD₃CN (1.95 ppm). The ¹³C chemical shifts are likewise relative to TMS and arise for the solvents CDCl₃ (77.2 ppm) and CD₃ CN (118.7 ppm). The ¹⁹F chemical shifts are relative to CFCl₃ and arise for the internal standards C₆F₆ (−162.9 ppm) or C₆H₅CF₃ (−63.9 ppm). The ³¹P chemical shifts are relative to H₃PO₄ (85%).

Example 1 Preparation of methyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₃, without alkali-metal or tetraalkylammonium fluoride

Dry methanol (0.697 g; 21.8 mmol) is added to cooled (0° C.) tris(pentafluoroethyl)phosphine oxide, (C₂F₅)₃P═O, (8.42 g; 20.8 mmol) in a 100 ml glass flask. A two-phase reaction mixture is observed. This is stirred at 0° C. for 1 h and subsequently at room temperature for 47 h. After about 20 minutes at room temperature, a clear and colourless reaction solution is observed. With increasing time at room temperature, the solution becomes a pale-yellow colour.

Composition in the ³¹P-NMR spectrum after 47 h at room temperature: methyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₃: 2% tris(pentafluoroethyl)phosphine oxide, (C₂F₅)₃P═O: 55% bis(pentafluoroethyl)phosphinate anion, [(C₂F₅)₂POO]⁻: 37% uncharacterised compounds: 6%

Example 2 Preparation of ethyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OC₂H₅, without catalyst (alkali-metal or tetraalkylammonium fluoride)

Dry ethanol (0.887 g; 19.3 mmol) is added to cooled (0° C.) tris(pentafluoro-ethyl)phosphine oxide, (C₂F₅)₃P═O, (7.97 g; 19.7 mmol) in a 100 ml glass flask. A two-phase reaction mixture is observed. After 1 h at 0° C., the reaction mixture is a clear and yellow-coloured solution, which is warmed to room temperature and stirred for a total of 47 h. With increasing time at room temperature, the solution becomes an orange-brown colour. Composition in the ³¹P-NMR spectrum after 47 h at room temperature: ethyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OC₂H₅: 29% tris(pentafluoroethyl)phosphine oxide, (C₂F₅)₃P═O: 39% bis(pentafluoroethyl)phosphinate anion, [(C₂F₅)₂POO]⁻: 26% uncharacterised compounds: 6%

Example 3 Preparation of methyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₃

Potassium fluoride (0.85 g; 14.6 mmol) is suspended in tris(pentafluoro-ethyl)phosphine oxide, (C₂F₅)₃P═O, (54.37 g; 134.6 mmol) in a 250 ml glass flask, cooled (0° C.), and dry methanol (4.43 g; 138.2 mmol) is added. The clear and colourless reaction solution is stirred at 0° C. for 1.5 h, warmed and stirred at room temperature for 43 h. After recondensation in vacuo (10⁻³ mbar) at 30° C. and double fractional distillation under reduced pressure (b.p.: 76 to 78° C. at 52 mbar), methyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₃, is isolated as clear and colourless liquid (23.65 g; 74.8 mmol) in a yield of 56% and a purity of 98%. The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 4.24 d (3H), ³J_(H,P)=11.1 Hz.

¹⁹F NMR: δ in ppm: −81.6 m (6F), −124.7 m (4F).

³¹P NMR: δ in ppm: 10.0 quin,m, ²J_(F,P)=87.8 Hz.

Example 4 Preparation of 1,3-dimethylimidazolium bis(pentafluoroethyl)phosphinate, [MMIM][(C₂F₅)₂P(O)O]

Methyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₃, (1.870 g; 5.9 mmol) is slowly added dropwise to cooled (0° C.) N-methylimidazole (0.424 g; 5.2 mmol) (exothermic) in a 25 ml glass flask. A white solid forms. The reaction mixture is diluted with 3.5 ml of n-hexane, warmed to room temperature and stirred for 30 min. The readily volatile constituents are removed in vacuo (10⁻³ mbar) at room temperature. 1,3-Dimethylimidazolium bis(pentafluoroethyl)phosphinate, [MMIM][(C₂F₅)₂P(O)O], (1.982 g; 5.0 mmol) is isolated as white solid in a yield of 96% and a purity of 97%. The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 8.53 br.s (1H), 7.36 d (2H), ⁴J_(H,H)=1.5; Hz; 3.8 s (6H).

¹⁹F NMR: δ in ppm: −81.5 m (6F), −126.2 d (4F), ²J_(F,P)=65.7 Hz.

³¹P NMR: δ in ppm: −1.5 quin, m, ²J_(F,P)=65.8 Hz.

Elemental Analysis

Experimental, %: N, 6.80, C, 27.02 and H, 2.20;

calculated for C₉H₉F₁₀N₂O₂P, %: N, 7.04, C, 27.15 and H, 2.28

Example 5 Preparation of methyldiphenylsulfonium bis(pentafluoroethyl)-phosphinate, [CH₃S(C₆H₅)₂][(C₂F₅)₂P(O)O]

Methyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₃, (1.77 g; 5.6 mmol) is slowly added dropwise to cooled (0° C.) diphenyl sulfide (1.01 g; 5.4 mmol) in a 25 ml glass flask. The two-phase reaction mixture is warmed and stirred at 45° C. for 17 h. The readily volatile constituents are removed in vacuo (10⁻³ mbar) at room temperature. Methyldiphenylsulfonium bis(pentafluoroethyl)phosphinate, [CH₃S(C₆H₅)₂][(C₂F₅)₂P(O)O], (2.31 g, 4.6 mmol) is isolated as pale-yellow and highly viscous liquid in a yield of 85% and a purity of 90%.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 7.93 d,m (4H), ³J_(H,H)=7.3 Hz; 7.80 t,m (2H), ³J_(H,H)=7.5 Hz; 7.71 t,m (4H), ³J_(H,H)=7.3 Hz; 3.65 s (3H).

¹⁹F NMR: δ in ppm: −81.3 m (6F), −126.0 d (4F), ²J_(F,P)=70.0 Hz.

³¹P NMR: δ in ppm: −1.2 quin,m, ²J_(F,P)=70.0 Hz.

Elemental Analysis

Experimental, %: C, 40.26; H, 2.37; and S, 6.27;

calculated for C₁₇H₁₃F₁₀O₂PS, %: C, 40.65; H, 2.61; and S, 6.38;

Example 6 Preparation of N,N-dimethylpyrrolidinium bis(pentafluoroethyl)-phosphinate, [MMPL][(C₂F₅)₂P(O)O]

Methyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₃, (3.15 g; 10.0 mmol) is slowly added dropwise to dry, cooled (0° C.) N-methylpyrrolidine (0.85 g; 10.0 mmol) (exothermic) in a 25 ml glass flask. A white suspension forms. The reaction mixture is diluted with 2 ml of n-hexane, warmed to room temperature and stirred for 30 min. The readily volatile constituents are removed in vacuo (10⁻³ mbar) at 35° C. N,N-Dimethylpyrrolidinium bis(pentafluoroethyl)phosphinate, [MMPL][(C₂F₅)₂P(O)O], (2.72 g; 6.8 mmol) is isolated as white solid in a yield of 68% and a purity of 98%.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 3.45 t,m (4H), ³J_(H,H)=7.3 Hz, 3.07 s (6H), 2.20 m (4H).

¹⁹F NMR: δ in ppm −81.5 m (6F), −126.1 d (4F), ²J_(F,P)=65.4 Hz. ³¹P NMR: δ in ppm −1.7 quin,m, ²J_(F,P)=65.4 Hz.

Melting point: 121° C.

Elemental Analysis

Experimental, %: N, 3.53, C, 30.06 and H, 3.49;

calculated for C₁₀H₁₄F₁₀NO₂P, %: N, 3.49, C, 29.94 and H, 3.52.

Example 7 Preparation of triethylmethylammonium bis(pentafluoroethyl)-phosphinate, [CH₃N(C₂H₅)₃][(C₂F₅)₂P(O)O]

Methyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₃, (1.83 g; 5.8 mmol) is slowly added dropwise to dry and cooled (0° C.) triethylamine (0.59 g; 5.9 mmol) (exothermic) in a 10 ml glass flask. A yellow solid forms. The reaction mixture is diluted with 10 ml of n-hexane, warmed to room temperature and stirred for 20 min. The readily volatile constituents are removed in vacuo (10⁻³ mbar) at room temperature. Triethylmethylammonium bis(pentafluoroethyl)phosphinate, [CH₃N(C₂H₅)₃][(C₂F₅)₂P(O)O], (2.19 g; 5.3 mmol) is isolated as pale-yellow solid in a yield of 91% and a purity of 99%.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 3.25 q (6H), ³J_(H,H)=7.3 Hz, 2.86 s (3H), 1.27 t,m (9H), ³J_(H,H)=7.3 Hz.

¹⁹F NMR: δ in ppm: −81.5 m (6F), −126.1 d (4F), ²J_(F,P)=65.4 Hz.

³¹P NMR: δ in ppm −1.7 quin, m, ²J_(F,P)=65.5 Hz.

Melting point: 107° C.

Elemental Analysis

Experimental, %: N, 3.40, C, 31.72 and H, 3.54;

calculated for C₁₁H₁₈F₁₀NO₂P, %: N, 3.36, C, 31.67 and H, 4.35.

Example 8 Preparation of N,N,N′,N′,O-pentamethylisouronium bis(pentafluoro-ethyl)phosphinate, [((CH₃)₂N)₂COCH₃][(C₂F₅)₂P(O)O]

Methyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₃, (3.76 g; 11.9 mmol) is slowly added dropwise to dry and cooled (0° C.) N,N,N′,N′-tetramethylurea (1.28 g; 11.0 mmol) in a 25 ml glass flask. The colourless reaction solution is warmed (room temperature), stirred for 22.5 h, and the readily volatile constituents are removed in vacuo (10⁻³ mbar) at room temperature. N,N,N′,N′,O-Pentamethylisouronium bis(pentafluoroethyl)-phosphinate, [((CH₃)₂N)₂COCH₃][(C₂F₅)₂P(O)O], (4.73 g; 10.9 mmol) is isolated as colourless, highly viscous liquid in quantitative yield and a purity of 99%.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 4.05 s (3H), 3.05 s (12H)

¹⁹F NMR: δ in ppm: −81.5 m (6F), −126.1 d (4F), ²J_(F,P)=65.6 Hz.

³¹P NMR: δ in ppm: −1.6 quin,m, ²J_(F,P)=65.5 Hz.

Elemental Analysis

Experimental, %: N, 6.36, C, 27.05 and H, 3.23;

calculated for C₁₀H₁₆F₁₀N₂O₃P, %: N, 6.47, C, 27.73 and H, 3.72.

Example 9 Preparation of N,N,N′,N′,N″-pentamethylguanidinium bis(pentafluoro-ethyl)phosphinate, [((CH₃)₂N)₂CNHCH₃][(C₂F₅)₂P(O)O]

Methyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₃, (3.22 g; 10.2 mmol) is slowly added dropwise to dry and cooled (0° C.) 1,1,2,2-tetra-methylguanidine (1.12 g; 9.7 mmol) (exothermic) in a 25 ml glass flask. The cloudy, highly viscous liquid formed spontaneously is warmed (room temperature), diluted with 10 ml of n-hexane, and the reaction mixture is stirred for 3 h. The readily volatile constituents are removed in vacuo (10⁻³ mbar) at 40° C. N,N,N′,N′,N″-Pentamethylguanidinium bis(pentafluoroethyl)-phosphinate, [((CH₃)₂N)₂CNHCH₃][(C₂F₅)₂P(O)O], (4.04 g; 9.4 mmol) is isolated as colourless, cloudy and highly viscous liquid in a yield of 97% and a purity of 88%.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 6.67 s (1H), 2.94 s (3H), 2.92 s (6H), 2.90 s (6H).

¹⁹F NMR: δ in ppm: −81.5 m (6F), −126.1 d (4F), ²J_(F,P)=66.1 Hz.

³¹P NMR: δ in ppm: −1.6 quin,m, ²J_(F,P)=66.1 Hz.

Elemental Analysis

Experimental, %: N, 9.83, C, 28.00 and H, 3.86;

calculated for C₁₀H₁₆F₁₀N₃O₂P, %: N, 9.74, C, 27.85 and H, 3.74.

Example 10 Preparation of N,N-butylmethylpyrrolidinium bis(pentafluoroethyl)-phosphinate, [BMPL][(C₂F₅)₂P(O)O]

Methyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₃, (3.67 g; 11.6 mmol) is slowly added dropwise to dry and cooled (0° C.) N-butyl-pyrrolidine (1.38 g; 11.2 mmol) (exothermic) in a 25 ml glass flask. A pale-yellow solid forms. The reaction mixture is warmed to room temperature, diluted with 10 ml of n-hexane and stirred for 16.5 h. The readily volatile constituents are removed in vacuo (10⁻³ mbar) at room temperature. N-Butyl-N-methylpyrrolidinium bis(pentafluoroethyl)phosphinate, [BMPL][(C₂F₅)₂P(O)O], (4.71 g; 10.7 mmol) is isolated as pale-yellow solid in a yield of 96% and a purity of 99%.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 3.43 m (4H), 3.25 m (2H), 2.96 s (3H), 2.17 m (4H), 1.74 m (2H), 1.40 t,q (2H), ³J_(H,H)=7.5 Hz, 0.99 t (3H), ³J_(H,H)=7.3 Hz.

¹⁹F NMR: δ in ppm: −81.5 m (6F), 126.1 d (4F), ²J_(F,P)=65.6 Hz.

³¹P NMR: δ in ppm: −1.6 quin,m, ²J_(F,P)=65.6 Hz.

Melting point: 118° C.

Elemental Analysis

Experimental, %: N, 3.16, C, 35.48 and H, 4.47;

calculated for C₁₃H₂₀F₁₀NO₂P, %: N, 3.16, C, 35.23 and H, 4.55.

Example 11 Preparation of 1-ethyl-3-methylimidazolium bis(pentafluoroethyl)-phosphinate, [EMIM][(C₂F₅)₂P(O)O]

Purified 1-ethyl-3-methylimidazolium chloride, [EMIM]Cl, (0.304 g; 2.1 mmol) is suspended in n-hexane (about 4 ml) in a 10 ml glass flask, cooled (0° C.), and methyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₃, (0.676 g; 2.1 mmol) is added. The reaction mixture is warmed (room temperature) and stirred for 26 h. The readily volatile constituents are removed in vacuo (10⁻³ mbar) at room temperature. 1-Ethyl-3-methylimidazolium bis(pentafluoroethyl)phosphinate, [EMIM][(C₂F₅)₂P(O)O], (0.86 g; 2.1 mmol) is isolated as pale-yellow, highly viscous liquid in quantitative yield with a purity of 99%.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 8.77 br.s (1H), 7.47 d,d (1H), ³J_(H,H)=1.8 Hz; 7.41 d,d (1H), ³J_(H,H)=1.8 Hz; 4.20 q (2H), ³J_(H,H)=7.3 Hz; 3.85 s (3H); 1.47 t (3H), ³J_(H,H)=7.3 Hz.

¹⁹F NMR: δ in ppm: −81.5 m (6F), −126.2 d (4F), ²J_(F,P)=66.8 Hz.

³¹P NMR: δ in ppm: −1.4 quin,m, ²J_(F,P)=66.9 Hz.

Example 12 Preparation of ethyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OC₂H₅

A) KF as Catalyst

Potassium fluoride (0.515 g; 8.9 mmol) is suspended in tris(pentafluoro-ethyl)phosphine oxide, (C₂F₅)₃P═O, (33.02 g; 81.7 mmol) in a 100 ml glass flask, cooled (0° C.), and dry ethanol (3.84 g; 83.3 mmol) is added. The clear and colourless reaction solution is stirred at 0° C. for 1 h and at room temperature for 20.5 h. After recondensation in vacuo (10⁻³ mbar) at 25° C. and subsequent fractional distillation under reduced pressure (b.p.: 69 to 70° C. at 38 mbar), ethyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OC₂H₅, is isolated as clear and colourless liquid (16.04 g; 48.6 mmol) in a yield of 59% and a purity of 98%.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 4.68 d,q (2H), ³J_(H,P)=8.3 Hz, ³J_(H,H)=7.1 Hz, 1.49 t (3H), ³J_(H,H)=7.1 Hz.

¹⁹F NMR: δ in ppm: −81.5 m (6F), −124.8 m (4F).

³¹P NMR: δ in ppm: 8.4 quin, ²J_(F,P)=87.8 Hz.

Elemental Analysis

Experimental, %: C, 21.27 and H, 1.32;

calculated for C₆H₅F₁₀O₂P, %: C, 21.83 and H, 1.53.

B) NaF as Catalyst

Sodium fluoride (0.043 g; 1.0 mmol) is suspended in tris(pentafluoroethyl)-phosphine oxide, (C₂F₅)₃P═O, (3.701 g; 9.2 mmol) in a 25 ml glass flask, cooled (0° C.), and dry ethanol (0.446 g; 9.7 mmol) is added. The clear and colourless reaction solution is stirred at 0° C. for 1 h, warmed and stirred at room temperature for 3.5 h. The formation of (C₂F₅)₂P(O)OC₂H₅ with a yield of 88% (detected by means of ³¹P and ¹⁹F NMR) is observed. Ethyl bis-(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OC₂H₅, is isolated as clear and colourless liquid using the method described in Example 12 A.

C) RbF as Catalyst

Rubidium fluoride (0.101 g; 1.0 mmol) is suspended in tris(pentafluoro-ethyl)phosphine oxide, (C₂F₅)₃P═O, (3.261 g; 8.1 mmol) in a 100 ml glass flask, cooled (0° C.), and dry ethanol (0.406 g; 8.8 mmol) is added. The clear and colourless reaction solution is stirred at 0° C. for 1 h, warmed and stirred at room temperature for 3.5 h. The formation of (C₂F₅)₂P(O)OC₂H₅ with a yield of 83% (detected by means of ³¹P and ¹⁹F NMR) is observed. Ethyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OC₂H₅, are isolated as clear and colourless liquid using the method described in Example 12 A.

D) CsF as Catalyst

Caesium fluoride (0.149 g; 1.0 mmol) is suspended in tris(pentafluoroethyl)-phosphine oxide, (C₂F₅)₃P═O, (3.732 g; 9.2 mmol) in a 100 ml glass flask, cooled (0° C.), and dry ethanol (0.481 g; 10.4 mmol) is added. The clear and colourless reaction solution is stirred at 0° C. for 1 h, warmed and stirred at room temperature for 3.5 h. The formation of (C₂F₅)₂P(O)OC₂H₅ with a yield of 84% (detected by means of ³¹P and ¹⁹F NMR) is observed. Ethyl bis-(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OC₂H₅, can be isolated as clear and colourless liquid using the method described in Example 12 A.

E) [N(CH₃)₄]F as Catalyst

Tetramethylammonium fluoride (0.095 g; 1.0 mmol) is suspended in tris-(pentafluoroethyl)phosphine oxide, (C₂F₅)₃P═O, (3.835 g; 9.5 mmol) in a 25 ml glass flask, cooled (0° C.), and dry ethanol (0.502 g; 10.9 mmol) is added. The clear and colourless reaction suspension is stirred at 0° C. for 1 h, warmed and stirred at room temperature for 3.5 h. The formation of (C₂F₅)₂P(O)OC₂H₅ with a yield of 93% (detected by means of ³¹P and ¹⁹F NMR) is observed. Ethyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OC₂H₅, can be isolated as clear and colourless liquid using the method described in Example 12 A.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 0.79 t (3H), ³J_(H,H)=7.2 Hz, 3.91 d,q (2H), ³J_(H,H)=7.2 Hz, ³J_(H,P)=8.2 Hz.

¹⁹F NMR: δ in ppm: −82.9 m (6F), −126.1 m (4F).

³¹P NMR: δ in ppm: 8.5 quin,m, ²J_(F,P)=89.2 Hz.

Example 13 Preparation of pentadeuteroethyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OC₂D₅

Potassium fluoride (0.105 g; 1.8 mmol) is suspended in cooled (0° C.) tris-(pentafluoroethyl)phosphine oxide, (C₂F₅)₃P═O, (6.727 g; 16.7 mmol) in a 100 ml glass flask, and hexadeuteroethanol (0.928 g; 17.8 mmol) is added. The clear and colourless reaction solution is stirred at 0° C. for 1 h, warmed and stirred at room temperature for 5 h. After recondensation in vacuo (10⁻³ mbar) at room temperature, pentadeuteroethyl bis(pentafluoroethyl)-phosphinate, (C₂F₅)₂P(O)OC₂D₅, is isolated as clear and colourless liquid (4.40 g; 13.1 mmol) in a yield of 78% and a purity of 96%.

The isolated product is characterised by means of ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹⁹F NMR: δ in ppm: −82.9 m (6F), −126.2 m (4F).

³¹P NMR: δ in ppm: 8.3 quin, m, ²J_(F,P)=88.1 Hz.

Example 14 Preparation of ethylmethylphenylsulfonium bis(pentafluoroethyl)phosphinate, [(CH₃)(C₂H₅)(C₆H₅)S][(C₂F₅)₂P(O)O]

Ethyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OC₂H₅, (4.247 g; 12.9 mmol) is added to thioanisole (1.553 g; 12.5 mmol) in a 25 ml glass flask. The reaction emulsion is warmed and stirred at 45° C. for 9 h. The more highly viscous, clear and colourless liquid forms. The readily volatile constituents are removed in vacuo (10⁻³ mbar) at room temperature. Ethylmethylphenylsulfonium bis(pentafluoroethyl)phosphinate, [(CH₃)(C₂H₅)(C₆H₅)S][(C₂F₅)₂P(O)O], (5.63 g; 12.4 mmol) is isolated as colourless, highly viscous liquid in quantitative yield and a purity of 98%.

¹H NMR in CD₃CN: δ in ppm: 7.99 d, m (2H), ³J_(H,H)=7.6 Hz, 7.83 t, m (1H), ³J_(H,H)=7.4 Hz, 7.73 t, m (2H), ³J_(H,H)=7.9 Hz, 3.66 m (2H), 3.24 s (3H), 1.28 t (3H), ³J_(H,H)=7.4 Hz.

¹⁹F NMR in CD₃CN: δ in ppm: −81.3 s (6F), −126.1 d (6F), ²J_(F,P)=66.4 Hz.

³¹P NMR in CD₃CN: δ in ppm: −1.4 quin,m, ²J_(F,P)=66.8 Hz.

Elemental Analysis

Experimental, %: C, 34.08; H, 2.84; and S, 6.74;

calculated for C₁₃H₁₃F₁₀O₂PS, %: C, 34.37; H, 2.88; and S, 7.06.

Example 15 Preparation of 1-ethyl-3-methylimidazolium bis(pentafluoroethyl)-phosphinate, [EMIM][(C₂F₅)₂P(O)O]

Ethyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OC₂H₅, (4.59 g; 13.9 mmol) is slowly added dropwise to dry and cooled (0° C.) N-methylimidazole (1.10 g; 13.4 mmol) (exothermic) in a 25 ml glass flask. After 45 minutes, a pale-yellow solid forms. The reaction mixture is warmed to room temperature, diluted with 4 ml of n-hexane and stirred for 45 minutes. The readily volatile constituents are removed in vacuo (10⁻³ mbar) at 40° C. 1-Ethyl-3-methylimidazolium bis(pentafluoroethyl)phosphinate,

[EMIM][(C₂F₅)₂P(O)O], (5.52 g; 13.4 mmol) is isolated as highly viscous, pale-yellow liquid in quantitative yield and a purity of 99%.

¹H NMR in CD₃CN: δ in ppm: 8.92 s (1H), 7.53 d,d (1H), ³J_(H,H)=1.8 Hz; 7.45 d,d (1H), ³J_(H,H)=1.8 Hz; 4.21 q (2H), ³J_(H,H)=7.3 Hz, 3.86 s (3H), 1.47 t (3H), ³J_(H,H)=7.3.

¹⁹F NMR in CD₃CN: δ in ppm: −81.5 m (6F), −126.2 d (4F), ²J_(F,P)=66.4 Hz.

³¹P NMR in CD₃CN: δ in ppm: −1.2 quin,m, ²J_(F,P)=66.7 Hz.

Elemental Analysis

Experimental, %: N, 6.78, C, 28.86 and H, 2.78; calculated for C₁₀H₁₁F₁₀N₂O₂P, %: N, 6.80, C, 29.14 and H, 2.69.

Viscosity Measurement

Dynamic viscosity: η=128 mPa·s (20° C.)

Kinematic viscosity: v=84 mm²/s (20° C.)

Density: ρ=1.527 g/cm³ (20° C.)

Example 16 Preparation of N-ethylpyridinium bis(pentafluoroethyl)phosphinate, [EPy][(C₂F₅)₂P(O)O]

Ethyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OC₂H₅, (3.956 g; 12.0 mmol) is slowly added dropwise to dry and cooled (0° C.) pyridine (0.941 g; 11.9 mmol) in a 25 ml glass flask. A pale-yellow, more highly viscous solution forms spontaneously. After 30 minutes at 0° C. and 6 h at room temperature, the reaction solution is a brown-orange colour. The readily volatile constituents are removed in vacuo (10⁻³ mbar) at 40° C. N-Ethylpyridinium bis(pentafluoroethyl)phosphinate, [EPy][(C₂F₅)₂P(O)O], (4.845 g; 11.8 mmol) can be isolated as highly viscous, intensely brown-orange liquid in quantitative yield and a purity of 99%.

¹H NMR in CD₃CN: δ in ppm: 8.88 d (2H), ³J_(H,H)=5.7 Hz, 8.54 t,t (1H), ³J_(H,H)=7.8 Hz, ⁴J_(H,H)=1.2 Hz, 8.05 m (2H), 4.64 q (2H), ³J_(H,H)=7.4, 1.61 t (3H), ³J_(H,H)=7.3 Hz.

¹⁹F NMR in CD₃CN: δ in ppm: −81.4 m (6F), −126.1 d (4F), ²J_(F,P)=66.1 Hz.

³¹P NMR in CD₃CN: δ in ppm: −1.3 quin,m, ²J_(F,P)=66.1 Hz.

Elemental Analysis

Experimental, %: N, 3.40, C, 32.28 and H, 2.76;

calculated for C₁₁H₁₀F₁₀NO₂P, %: N, 3.42, C, 32.29 and H, 2.46.

Viscosity Measurement

Dynamic viscosity: η=97 mPa·s (20° C.)

Kinematic viscosity: v=63 mm²/s (20° C.)

Density: ρ=1.537 g/cm³ (20° C.)

Example 17 Preparation of tributylethylphosphonium bis(pentafluoroethyl)-phosphinate, [(C₄H₉)₃PC₂H₅][(C₂F₅)₂P(O)O]

Ethyl bis(pentafluoroethyl)phosphinate (1.538 g; 4.7 mmol) is added to cooled (0° C.) tributylphosphine (0.953 g; 4.7 mmol) in a 25 ml glass flask. The reaction mixture is stirred at 0° C. for 1 h, with initially a two-phase system and later the formation of a solid being observed. The reaction mixture is diluted with 10 ml of n-hexane, warmed and stirred at room temperature for 5.5 h. The readily volatile constituents are removed in vacuo (10⁻³ mbar) at 35° C. Tributylethylphosphonium bis(pentafluoroethyl)phosphinate, [(C₄H₉)₃PC₂H₅][(C₂F₅)₂P(O)O], (2.262 g; 4.2 mmol) is isolated as colourless solid in a yield of 89% and a purity of 98%.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 2.13 m (8H), 1.50 m (12H), 1.20 d,t (3H), ³J_(H,P)=18.2 Hz, ³J_(H,H)=7.6 Hz; 0.97 t (9H), ³J_(H,H)=7.1 Hz.

¹⁹F NMR: δ in ppm: −81.4 m (6F), −126.1 d (4F), ²J_(F,P)=65.4 Hz.

³¹P NMR: δ in ppm: 35.4 m (1P); −1.7 quin,m, ²J_(F,P)=65.3 Hz.

Melting point: 44° C.

Elemental Analysis

Experimental, %: C, 41.20 and H, 6.44;

calculated for C₁₈H₃₂F₁₀NO₂P₂, %: C, 40.61 and H, 6.06

Example 18 Preparation of 2-(allyloxy)ethyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₂CH₂OCH₂CH═CH₂

Potassium fluoride (0.277 g; 4.8 mmol) is suspended in tris(pentafluoro-ethyl)phosphine oxide, (C₂F₅)₃P═O, (16.783 g; 41.5 mmol) in a 100 ml glass flask, cooled (0° C.), and 2-allyloxyethanol (4.188 g; 41.0 mmol) is added. The two-phase reaction suspension is stirred at 0° C. for 3 h and at room temperature for 20 h. After recondensation in vacuo (10⁻³ mbar) at 50° C. (decomposition is observed from 40° C.) and subsequent fractional distillation under reduced pressure (b.p.: 40 to 42° C. at 3.8·10⁻³ mbar), 2-(allyloxy)-ethyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₂CH₂OCH₂—CH═CH₂, can be isolated as clear and colourless liquid (7.083 g; 18.3 mmol) in a yield of 45% and a purity of 96%. The product is stored at −20° C.

¹H NMR in CD₃CN: δ in ppm: 5.93 m (1H), 5.32 d,m (1H), ³J_(trans(H,H))=17.1 Hz; 5.20 d,m (1H), ³J_(cis(H,H))=10.5 Hz, 4.69 m (2H); 4.04 d,m (2H), ³J_(H,H)=5.5 Hz, 3.75 m (2H).

¹⁹F NMR in CD₃CN: δ in ppm: −81.3 m (6F), −124.4 m (4F).

³¹P NMR in CD₃CN: δ in ppm: 8.8 quin,m, ²J_(F,P)=88.4 Hz.

Example 19 Preparation of N-[2-(allyloxy)ethyl]pyridinium bis(pentafluoroethyl)-phosphinate, [CH₂═CHCH₂OCH₂CH₂Py][(C₂F₅)₂P(O)O]

2-(Allyloxy)ethyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)O—CH₂CH₂OCH₂CH═CH₂, (2.407 g; 6.2 mmol) is slowly added dropwise to dry and cooled (0° C.) pyridine (0.502 g; 6.3 mmol) in a 25 ml glass flask. An orange, more highly viscous solution forms spontaneously, which is stirred at 0° C. for 1 h, warmed and stirred at room temperature for 2 h. The readily volatile constituents are removed in vacuo (10⁻³ mbar) at room temperature. N-[2-(Allyloxy)ethyl]pyridinium bis(pentafluoroethyl)phosphinate, [CH₂═CHCH₂OCH₂CH₂Py][(C₂F₅)₂P(O)O], is isolated (2.829 g; 6.1 mmol) as highly viscous, intensely red-brown liquid in quantitative yield and a purity of 89%.

¹H NMR in CD₃CN: δ in ppm: 8.87 d,m (2H), ³J_(H,H)=5.4 Hz, 8.57 t,t (1H), ³J_(H,H)=7.8 Hz, ⁴J_(H,H)=1.3 Hz, 8.07 t (2H), ³J_(H,H)=7.1 Hz, 5.80 m (1H), 5.19 d,m (1H), ³J_(trans(H,H))=17.3 Hz, 5.14 d,m (1H), ³J_(cis(H,H))=10.5 Hz, 4.78 m (2H), 3.97 d,m (2H), ³J_(H,H)=5.4 Hz; 3.90 t (2H), ³J_(H,H)=4.9 Hz.

¹⁹F NMR in CD₃CN: δ in ppm: −81.4 m (6F), −126.1 d (4F), ²J_(F,P)=66.2 Hz.

³¹P NMR in CD₃CN: δ in ppm: −1.3 quin,m, ²J_(F,P)=66.2 Hz.

Elemental Analysis

Experimental, %: N, 3.01, C, 36.14 and H, 3.03;

calculated for C₁₄H₁₄F₁₀NO₃P, %: N, 2.80, C, 35.96 and H, 3.10.

Example 20 Preparation of 3-[2-(allyloxy)ethyl]-1-methylimidazolium bis(penta-fluroethyl)phosphinate, [CH₂═CHCH₂OCH₂CH₂MIM][(C₂F₅)₂P(O)O]

2-(Allyloxy)ethyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₂CH₂—OCH₂CH═CH₂, (4.135 g; 10.7 mmol) is slowly added dropwise to dry and cooled (0° C.) N-methylimidazole (0.793 g; 9.7 mmol) (exothermic) in a 50 ml glass flask. A pale-yellow, more highly viscous solution forms spontaneously, which is stirred at 0° C. for 1.5 h, warmed and stirred at room temperature for 5 h. The readily volatile constituents are removed in vacuo (10⁻³ mbar) at room temperature. 3-[2-(Allyloxy)ethyl]-1-methylimidazolium bis(pentafluoroethyl)phosphinate, [CH₂═CHCH₂OCH₂CH₂MIM][(C₂F₅)₂—P(O)O], (4.521 g; 9.7 mmol) is isolated as highly viscous, pale-yellow liquid in quantitative yield and a purity of 94%.

¹H NMR in CD₃CN: δ in ppm: 8.81 s (1H), 7.51 d,d (1H), ⁴J_(H,H)=1.8 Hz, 7.45 d,d (1H), ⁴J_(H,H)=1.8 Hz, 5.88 m (1H), 5.25 d,m (1H), ³J_(trans(H,H))=17.3 Hz; 5.17 d,m (1H), ³J_(cis(H,H))=10.5 Hz, 4.35 m (2H), 4.00 d,m (2H), ³J_(H,H)=5.5 Hz, 3.88 s (3H), 3.76 m (2H).

¹⁹F NMR in CD₃CN: δ in ppm: −81.4 m (6F), −126.2 d (4F), ²J_(F,P)=66.6 Hz.

³¹P NMR in CD₃CN: δ in ppm: −1.3 quin,m, ²J_(F,P)=66.8 Hz.

Elemental Analysis

Experimental, %: N, 5.78, C, 33.09 and H, 3.17;

calculated for C₁₃H₁₅F₁₀N₂O₃P, %: N, 5.98, C, 33.34 and H, 3.23.

Example 21 Preparation of 2-(2′,2′,2′-trifluoroethoxy)ethyl bis(pentafluoroethyl)-phosphinate, (C₂F₅)₂P(O)OCH₂CH₂OCH₂CF₃

Potassium fluoride (0.228 g; 3.9 mmol) is suspended in tris(pentafluoro-ethyl)phosphine oxide, (C₂F₅)₃P═O, (14.697 g; 36.4 mmol) in a 100 ml glass flask, cooled (0° C.), and 2,2,2-trifluoroethoxyethanol (5.184 g; 36.0 mmol) is added. The white reaction suspension is stirred at 0° C. for 2 h and at room temperature for 21.5 h. After recondensation in vacuo (10⁻³ mbar) at 70° C. and subsequent fractional distillation under reduced pressure (b.p.: 27 to 28° C. at 1·10⁻³ mbar), 2-(2′,2′,2′-trifluoroethoxy)ethyl bis(pentafluoroethyl)-phosphinate, (C₂F₅)₂P(O)OCH₂CH₂OCH₂CF₃, is isolated as clear and colourless liquid (6.041 g; 14.1 mmol) in a yield of 39% and a purity of 96%. Decomposition is observed after a few minutes. The product is stored at −20° C.

¹H NMR in CD₃CN: δ in ppm: 4.70 m (2H), 4.00 q (2H), ³J_(H,F)=8.9 Hz, 3.95 m (2H).

¹⁹F NMR in CD₃CN: δ in ppm: −75.3 t (3F), ³J_(H,F)=8.9 Hz; −81.3 m (6F); −124.5 m (4F).

³¹P NMR in CD₃CN: δ in ppm: 9.0 quin,m, ²J_(F,P)=88.6 Hz.

Example 22 Preparation of 1-methyl-3-[2-(2′,2′,2′-trifluoroethoxy)ethylimidazolium bis(pentafluoroethyl)phosphinate, [CF₃CH₂OCH₂CH₂MIM][(C₂F₅)₂—P(O)O]

2-(2′,2′,2′-Trifluoroethoxy)ethyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂—P(O)OCH₂CH₂OCH₂CF₃, (3.589 g; 8.4 mmol) is slowly added dropwise to dry and cooled (0° C.) N-methylimidazole (0.726 g; 8.8 mmol) in a 10 ml glass flask. A pale-yellow, more highly viscous solution forms spontaneously, which is stirred at 0° C. for 1 h, warmed and stirred at room temperature for 3 h. The readily volatile constituents are removed in vacuo (10⁻³ mbar) at room temperature. 1-Methyl-3-[2-(2′,2′,2′-trifluoroethoxy)-ethylimidazolium bis(pentafluoroethyl)phosphinate, [CF₃CH₂OCH₂CH₂MIM][(C₂F₅)₂P(O)O], (4.253 g; 8.3 mmol) is isolated as highly viscous, pale-yellow liquid in quantitative yield and a purity of 95%.

¹H NMR in CD₃CN: δ in ppm: 8.84 s (1H), 7.51 d,d (1H), ⁴J_(H,H)=1.8 Hz, 7.46 d,d (1H), ⁴J_(H,H)=1.8 Hz, 4.39 m (2H), 4.00 q (2H), ³J_(H,F)=9.0 Hz, 3.98 t (2H), ³J_(H,H)=4.8 Hz, 3.88 s (3H).

¹⁹F NMR in CD₃CN: δ in ppm: −75.3 t (3H), ³J_(H,F)=9.0 Hz, −81.5 m (6F), −126.2 d (4F), ²J_(F,P)=66.4 Hz.

³¹P NMR in CD₃CN: δ in ppm: −1.3 quin,m, ²J_(F,P)=66.4 Hz.

Elemental Analysis

Experimental, %: N, 5.53, C, 28.77 and H, 2.40;

calculated for C₁₂H₁₂F₁₃N₂O₃P, %: N, 5.49, C, 28.25 and H, 2.37.

Example 23 Preparation of phenyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂—P(O)OC₆H₅

Potassium fluoride (0.122 g; 2.1 mmol) is suspended in cooled (0° C.) tris(pentafluoroethyl)phosphine oxide (7.378 g; 18.3 mmol) in a 100 ml glass flask, and phenol (1.797 g; 19.1 mmol) is added. The reaction suspension is warmed and stirred at 80° C. for 4.5 h. A pale-brown reaction suspension is then observed. After recondensation in vacuo (10⁻³ mbar) at 40° C., phenyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OC₆H₅, is isolated as clear and colourless liquid (3.127 g; 8.3 mmol) in a yield of 45% and a purity of 90%.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN film.

¹H NMR: δ in ppm: 6.29 m (5H).

¹⁹F NMR: δ in ppm: −82.4 m (6F), −124.8 m (4F).

³¹P NMR: δ in ppm: 4.5 quin,m, ²J_(F,P)=91.1 Hz.

Example 24 Preparation of 9-decyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂—P(O)OCH₂(CH₂)₇CH═CH₂

Potassium fluoride (0.138 g; 2.4 mmol) is suspended in tris(pentafluoro-ethyl)phosphine oxide (9.26 g; 22.9 mmol) in a 100 ml glass flask, and 9-decen-1-ol (3.387 g; 21.7 mmol) is added. During the addition, the reaction mixture warms and is cooled (0° C.). When the addition is complete, the orange reaction solution is warmed and stirred at room temperature for 20 h. 9-decyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)⁻OCH₂(CH₂)₇CH═CH₂, is isolated as clear and colourless liquid (4.66 g; 10.6 mmol) in a yield of 49% and a purity of 94% by fractional distillation under reduced pressure (b.p.: 70 to 74° C. at 2.5·10⁻¹ mbar).

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 5.85 m (1H), 5.02 d,m (1H), ³J_(trans(H,H))=17.1 Hz, 4.98 d, m (1H), ³J_(cis(H,H))=10.2 Hz, 4.61 d, t (2H), ³J_((H,P))=7.3 Hz, ³J_((H,H))=6.4 Hz, 2.07 m (2H), 1.82 m (2H), 1.34 m (10H).

¹⁹F NMR: δ in ppm: −79.5 m (6F), −122.7 m (4F).

³¹P NMR: δ in ppm: 7.5 quin, m, ²J_(F,P)=88.0 Hz.

Example 25 Preparation of propargyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₂C≡CH

Potassium fluoride (0.262 g; 4.5 mmol) is suspended in cooled (0° C.) tris(pentafluoroethyl)phosphine oxide (14.930 g; 37.0 mmol) in a 100 ml glass flask, and propargyl alcohol (2.055 g; 36.7 mmol) is added. The yellow reaction solution is slowly warmed (about 6 h) and stirred at room temperature for 19.5 h. Volatile components are removed in vacuo (10⁻³ mbar) at 0° C. After recondensation in vacuo (10⁻³ mbar) at room temperature, propargyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₂C≡CH, is isolated as clear and colourless liquid (7.831 g; 23.0 mmol) in a yield of 63% and a purity of 95%. The ester becomes a brown colour after a few minutes at room temperature and is therefore stored at 3° C.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN film.

¹H NMR: δ in ppm: 4.48 d, d (2H), ³J_((H,P))=10.3 Hz, ⁴J_((H,H))=2.2 Hz, 2.29 m (1H).

¹⁹F NMR: δ in ppm: −82.5 m (6F), −125.4 m (4F).

³¹P NMR: δ in ppm: 10.1 quin, m, ²J_(F,P)=90.6 Hz.

Example 26 Preparation of 1-propargyl-3-methylimidazolium bis(pentafluoroethyl)-phosphinate, [CH≡CCH₂MIM][(C₂F₅)₂P(O)O]

Propargyl bis(pentafluoroethyl)phosphinate (11.18 g; 32.9 mmol) is slowly added dropwise to cooled (0° C.) N-methylimidazole (2.22 g; 27.1 mmol) in a 100 ml glass flask. In an exothermic reaction, an orange solid is formed, which is warmed and stirred at room temperature for 1.5 h. After drying in vacuo (10⁻³ mbar) at room temperature, 1-propargyl-3-methylimidazolium bis(pentafluoroethyl)phosphinate, [CH≡CCH₂MIM][(C₂F₅)₂P(O)O], (11.14 g; 26.3 mmol) is isolated as pale-orange solid in a yield of 99% and a purity of 97%. The coloured solid can be washed colourless with dichloromethane and n-hexane.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 8.72 br.s (1H), 7.51 m (1H), 7.42 m (1H), 5.03 d (2H), ⁴J_(H,H)=2.5 Hz, 3.87 s (3H), 3.07 t (1H), ⁴J_(H,H)=2.5 Hz.

¹⁹F NMR: δ in ppm: −81.5 m (6F), −126.2 d (4F), ²J_(F,P)=65.3 Hz.

³¹P NMR: δ in ppm: −1.5 quin, ²J_(F,P)=65.5 Hz.

Elemental Analysis

Experimental, %: N, 6.55, C, 31.21 and H, 2.02;

calculated for C₁₁H₉F₁₀N₂O₂P, %: N, 6.64, C, 31.30 and H, 2.15

Example 27 Preparation of 1-methyl-1-propargylpyrrolidinium bis(pentafluoro-ethyl)phosphinate, [CH≡CCH₂MPL][(C₂F₅)₂P(O)O]

Propargyl bis(pentafluoroethyl)phosphinate (6.44 g; 18.9 mmol) is added to cooled (0° C.) N-methylpyrrolidine (1.60 g; 18.7 mmol) in a 25 ml glass flask. In an exothermic reaction, a yellow solid forms spontaneously. This is suspended in n-hexane (12 ml), stirred at 0° C. for 30 minutes, warmed (room temperature), diluted with further n-hexane (8 ml) and stirred at room temperature for 17 h. The readily volatile constituents are removed in vacuo (10⁻³ mbar) at 50° C. 1-Methyl-1-propargylpyrrolidinium bis(pentafluoro-ethyl)phosphinate, [CH≡CCH₂MPL][(C₂F₅)₂P(O)O], (7.47 g; 17.6 mmol) is isolated as pale-beige solid in a yield of 94% and a purity of 98%.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 4.21 d (2H), ⁴J_(H,H)=2.5 Hz, 3.56 m (4H), 3.20 t (1H), ⁴J_(H,H)=2.5 Hz, 3.14 s (3H), 2.21 m (4H).

¹⁹F NMR: δ in ppm: −81.5 m (6F), −126.1 d (4F), ²J_(F,P)=65.9 Hz.

³¹P NMR: δ in ppm: −1.5 quin, m, ²J_(F,P)=65.9 Hz.

Melting point: 70° C.

Elemental Analysis

Experimental, %: N, 3.30, C, 34.11 and H, 3.34;

calculated for C₁₂H₁₄F₁₀NO₂P, %: N, 3.29, C, 33.90 and H, 3.32

Example 28 Preparation of trioctylpropargylammonium bis(pentafluoroethyl)-phosphinate, [(C₈H₁₇)₃NCH₂C≡CH][(C₂F₅)₂P(O)O]

Propargyl bis(pentafluoroethyl)phosphinate (4.131 g; 12.1 mmol) is slowly added dropwise to cooled (0° C.) trioctylamine (4.333 g; 12.3 mmol) in a 100 ml glass flask. An orange, more highly viscous solution forms spontaneously, which is warmed to room temperature. The readily volatile constituents are removed in vacuo (10⁻³ mbar) at room temperature to 120° C. Trioctylpropargylammonium bis(pentafluoroethyl)phosphinate, [(C₈H₁₇)₃—NCH₂C≡CH][(C₂F₅)₂P(O)O], (7.646 g; 11.0 mmol) is isolated as pale-orange liquid in a yield of 91% and a purity of 97%.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 4.11 m (2H); 3.25 m (6H); 2.92 m (1H); 1.67 m (6H); 1.34 m (30H); 0.92 M (9H).

¹⁹F NMR: δ in ppm: −81.4 m (6F), −126.1 d (4F), ²J_(F,P)=66.0 Hz.

³¹P NMR: δ in ppm: −1.7 quin,m, ²J_(F,P)=66.0 Hz.

Elemental Analysis

Experimental, %: N, 2.03, C, 54.79 and H, 8.08;

calculated for C₃₁H₅₄F₁₀NO₂P, %: N, 2.02, C, 53.67 and H, 7.85

Example 29 Preparation of ethyl bis(nonafluorobutyl)phosphinate, (C₄F₉)₂P(O)OC₂H₅

Potassium fluoride (0.158 g; 8.9 mmol) is suspended in cooled (0° C.) tris-(nonafluorobutyl)phosphine oxide, (C₄F₉)₃P═O, (18.57 g; 26.4 mmol) in a 100 ml glass flask, and dry ethanol (1.256 g; 27.3 mmol) is added. The clear and colourless reaction solution is stirred at 0° C. for 2 h and at room temperature for 64.5 h and recondensed in vacuo (10⁻³ mbar) at room temperature to 50° C. After recondensation and subsequent fractional distillation in vacuo (4.3·10⁻³ mbar), ethyl bis(nonafluorobutyl)phosphinate, (C₄F₉)₂P(O)OC₂H₅, is isolated as clear and colourless liquid (4.82 g; 9.1 mmol) in a yield of 34% (b.p.: 40-41° C. at 4.3·10⁻³ mbar).

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 3.78 d,q (2H, CH₂), ³J_(H,P)=³J_(H,H)=7.6 Hz, 0.64 t (3H, CH₃), ³J_(H,H)=7.1 Hz.

¹⁹F NMR: δ in ppm: −84.0 t,m (6F, 2CF₃), ³J_(F,F)=9.7 Hz, −122.2 m (8F, 4CF₂), −128.4 t,m (4F, 2CF₂), ³J_(F,F)=13.7 Hz.

³¹P NMR: δ in ppm: 8.8 quin, ²J_(F,P)=90.0 Hz.

Example 30 Preparation of 1-ethyl-3-methylimidazolium bis(nonafluorobutyl)-phosphinate, [EMIM][(C₄F₉)₂P(O)O]

Ethyl bis(nonafluorobutyl)phosphinate, (C₄F₉)₂P(O)OC₂H₅, (3.834 g; 7.2 mmol) is slowly added to cooled (0° C.) N-methylimidazole (0.458 g; 5.6 mmol) in a 25 ml glass flask. An exothermic reaction and two orange phases are observed. After a few minutes, a green-coloured, more highly viscous solution forms. This is stirred at 0° C. for 2.5 h and at room temperature for 41 h. 1-Ethyl-3-methylimidazolium bis(nonafluorobutyl)phosphinate, [EMIM][(C₄F₉)₂P(O)O], (3.233 g; 5.3 mmol) can be isolated as a highly viscous, green liquid in a yield of 95% and a purity of 95% by purification in vacuo (10⁻³ mbar) at room temperature to 50° C.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 8.82 br.s (1H), 7.48 m (1H); 7.41 m (1H), 4.21 q (2H), ³J_(H,H)=7.4 Hz, 3.86 s (3H), 1.47 t (3H), ³J_(H,H)=7.4 Hz.

¹⁹F NMR: δ in ppm: −81.5 t, m (6F), ³J_(F,F)=9.9 Hz, −121.7 m (4F), −122.6 d, m (4F), ²J_(F,P)=67.7 Hz, 126.5 m (4F).

³¹P NMR: δ in ppm: 0.1 quin, m ²J_(F,P)=67.7 Hz.

Elemental Analysis

Experimental, %: N, 4.05; C, 26.79; and H, 1.88;

calculated for C₁₄H₁₁F₁₈N₂O₂P, %: N, 4.58; C, 27.47; and H, 1.81

Example 31 Preparation of 3-bromopropyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₂CH₂CH₂Br

Potassium fluoride (0.227 g; 3.9 mmol) is suspended in cooled (0° C.) tris-(pentafluoroethyl)phosphine oxide, (C₂F₅)₃P═O, (13.773 g; 34.1 mmol) in a 100 ml glass flask, and pale-yellow 3-bromopropan-1-ol (4.790 g; 34.5 mmol) is added. The two-phase reaction mixture is warmed and stirred at room temperature for 20 h. After condensation in vacuo (10⁻³ mbar) at room temperature and double fractional distillation under reduced pressure (b.p.: 76 to 78° C. at 7.6 mbar), 3-bromopropyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₂CH₂CH₂Br, can be isolated as clear and colourless liquid (5.137 g; 12.1 mmol) in a yield of 35% and a purity of 96%.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 4.74 d, t (2H), ³J_(H,P)=6.8 Hz, ³J_(H,H)=6.0 Hz; 3.56 t (2H), ³J_(H,H)=6.4 Hz; 2.36 quin, m (2H), ³J_(H,H)=6.2 Hz.

¹⁹F NMR: δ in ppm: −81.2 m (6F); −124.3 m (4F).

³¹P NMR: δ in ppm: 8.9 quin, m, ²J_(F,P)=88.5 Hz.

Example 32 Preparation of 2,2,3,3,4,4,5,5-octafluoropentyl bis(pentafluoroethyl-) phosphinate, (C₂F₅)₂P(O)OCH₂CF₂CF₂CF₂CF₂H

Potassium fluoride (0.185 g; 3.2 mmol) is suspended in cooled (0° C.) tris-(pentafluoroethyl)phosphine oxide, (C₂F₅)₃P═O, (9.957 g; 24.6 mmol) in a 100 ml glass flask, and 2,2,3,3,4,4,5,5-octafluoropentan-1-ol (5.491 g; 23.7 mmol) is added dropwise. The reaction suspension is warmed and stirred at room temperature for 46.5 h. After condensation in vacuo (10⁻³ mbar) at room temperature to 60° C. and double fractional distillation in vacuo (6.10⁻³ mbar) (b.p.: 31 to 32° C.), 2,2,3,3,4,4,5,5-octafluoropentyl bis-(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₂CF₂CF₂CF₂CF₂H, can be isolated as clear and colourless liquid (1.603 g; 3.1 mmol) in a yield of 13% and a purity of 98%.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 6.44 t, t (1H), ²J_(H,F)=51.1 Hz, ³J_(H,F)=5.3 Hz; 5.11 t, d (2H), ³J_(H,F)=12.9 Hz, ³J_(H,P)=8.0 Hz.

¹⁹F NMR: δ in ppm: −81.3 m (6F); −121.7 m (2F); −123.8 m (4F); −125.5 m (2F); −130.7 m (2F); −139.4 d,m (2F), ²J_(H,F)=51.1 Hz.

³¹P NMR: δ in ppm: 10.6 quin, m, ²J_(F,P)=92.2 Hz.

Example 33 Preparation of 1-(3-bromopropyl)-3-methylimidazolium bis(pentafluoroethyl)phosphinate, [BrCH₂CH₂CH₂MIM][(C₂F₅)₂P(O)O]

3-Bromopropyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₂—CH₂CH₂Br, (4.710 g; 11.1 mmol) is slowly added dropwise to cooled (0° C.) N-methylimidazole (0.907 g; 11.0 mmol) (exothermic) in a 50 ml glass flask. It The colourless, more highly viscous and slightly cloudy reaction mixture is stirred at 0° C. for 1 h and at room temperature for 3 h and purified in vacuo (10⁻³ mbar) at room temperature. 1-(3-Bromopropyl)-3-methylimidazolium bis(pentafluoroethyl)phosphinate, [BrCH₂CH₂CH₂MIM][(C₂F₅)₂P(O)O], (5.286 g; 10.5 mmol) can be isolated as colourless, highly viscous and slightly cloudy liquid in a yield of 95% and a purity of 90%.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 8.83 br.s (1H); 7.50 d, m (1H), ⁴J_(H,H)=1.8 Hz; 7.44 d, m (1H), ⁴J_(H,H)=1.8 Hz; 4.32 t (2H), ³J_(H,H)=7.0 Hz; 3.86 s (3H); 3.46 t (2H), ³J_(H,H)=6.5 Hz; 2.40 quin (2H), ³J_(H,H)=6.8 Hz.

¹⁹F NMR: δ in ppm: −81.4 m (6F); −126.1 d (4F), ²J_(F,P)=66.3 Hz.

³¹P NMR: δ in ppm: −1.3 quin, m, ²J_(F,P)=66.3 Hz.

Elemental Analysis

Experimental, %: N, 6.03, C, 25.84 and H, 2.35;

calculated for C₁₁H₁₂BrF₁₀N₂O₂P, %: N, 5.55, C, 23.16 and H, 2.39

Example 34 Preparation of methyltriphenoxyphosphonium bis(pentafluoro-ethyl)phosphinate, [(C₆H₅O)₃PCH₃][(C₂F₅)₂P(O)O]

Methyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₃, (2.755 g; 8.7 mmol) is added at room temperature to triphenyl phosphite, P(OC₆H₅)₃, (2.075 g; 6.7 mmol) in a 10 ml glass flask. The two-phase reaction mixture is warmed and stirred at 60° C. for 5.5 h. A cloudy and colourless reaction mixture forms, that is stirred at RT for 16 h and at 60° C. for 5 h. Methyl bis(pentafluoroethyl)phosphinate, (C₂F₅)₂P(O)OCH₃, (0.380 g; 1.2 mmol) is added again, and the mixture is again stirred at 60° C. for 5.5 h. Methyltriphenoxyphosphonium bis(pentafluoroethyl)phosphinate, [(C₆H₅O)₃PCH₃]-[(C₂F₅)₂P(O)O], can be isolated as white and crystalline solid (3.827 g; 6.1 mmol) in a yield of 91% and a purity of 89% by purification in vacuo (10⁻³ mbar) at 80° C.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

¹H NMR: δ in ppm: 7.56 t, m (6H), ³J_(H,H)=7.8 Hz; 7.49 t, m (3H), ³J_(H,H)=7.3 Hz; 7.35 d, m (6H), ³J_(H,H)=7.8 Hz; 2.62 d (3H), ²J_(H,P)=17.0 Hz.

¹⁹F NMR: δ in ppm: −81.4 m (6F); −126.1 d (4F), ²J_(F,P)=72.6 Hz.

³¹P NMR: δ in ppm: 41.5 q (1P), ²J_(H,P)=17.0 Hz; −1.1 quin, m (1P), ²J_(F,P)=72.6 Hz.

Elemental Analysis

Experimental, %: C, 43.45 and H, 2.91;

calculated for C₂₃H₁₅F₁₀O₅P₂, %: C, 44.11 and H, 2.90

Example 35 Preparation of 2-tris(pentafluoroethyl)-1,3,2-dioxaphosphinane, (C₂F₅)₃P(O₂C₃H₆)

Potassium fluoride (0.069 g; 1.2 mmol) is suspended in cooled (0° C.) tris-(pentafluoroethyl)phosphine oxide, (C₂F₅)₃P═O, (4.131 g; 10.2 mmol) in a 25 ml flask, and propane-1,3-diol (0.800 g; 10.5 mmol) is added. The colourless reaction suspension is stirred at 0° C. for 1.5 h and at RT for 48 h and subsequently condensed at RT in vacuo. 2-Tris(pentafluoroethyl)-1,3,2-dioxaphosphinane is isolated as colourless solid (0.708 g; 1.5 mmol) in a yield of 30% and a purity of 91% by sublimation.

The isolated product is characterised by means of ¹H, ¹⁹F and ³¹P NMR spectra in CD₃CN.

1H: 1.99 (m, 2H), 4.55 (m, 4H)

19F: −110.0 (dm, ²J(¹⁹F—³¹P)=87.3 Hz, 6F), −79.2 (m, 9F)

31P: −54.1 (sepm, ²J(¹⁹F—³¹P)=87.1 Hz, 1P)

Elemental Analysis

Experimental, %: C, 23.39; H, 1.31;

calculated for C₉H₆F₁₅O₂P, %: C, 23.29; H, 1.34 

The invention claimed is:
 1. A process for preparing a phosphinic acid ester of formula (I) (C_(n)F_(2n+1−y)H_(y))₂P(O)OR  (I), where n in each case, independently of one another, denotes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, y in each case, independently of one another, denotes 0, 1, 2, 3 or 4, R denotes unsubstituted or substituted phenyl, a straight-chain or branched, unfluorinated or partially fluorinated or deuterated alkyl group having 1 to 30 C atoms or a straight-chain or branched, unfluorinated or partially fluorinated alkenyl or alkynyl group having 3 to 30 C atoms, where R may be partially substituted by halogen and/or partially substituted by —OH, —C(O)OH, N(CH₃)₂ and —CN and where one or two carbon atoms of the alkyl, alkenyl or alkynyl group which are not adjacent and are not in the α-position to the oxygen atom or to carbon atoms of the double bond or triple bond may be replaced by atoms and/or atom groups selected from the group consisting of —O, S, S(O)—, —SO₂—, —C(O)—, —C(O)O— and —N(R′)— and R′ in each case, independently of one another, denotes H, a straight-chain or branched, unfluorinated or partially fluorinated alkyl group having 1 to 18 C atoms, saturated C₃- to C₇-cycloalkyl, unsubstituted or substituted phenyl, comprising reacting a phosphine oxide of formula (II) (C_(n)F_(2n+1−y)H_(y))₃P(O)  (II), where n and y have a meanings indicated for formula (I), with an alcohol or phenol R—OH in the presence of alkali-metal fluoride or tetraalkylammonium fluoride, where R has a meaning indicated for formula (I), where the water content in the reaction is in total a maximum of 1000 ppm and where alkyl in tetraalkylammonium in each case, independently of one another, denotes a straight-chain or branched alkyl group having 1 to 10 C atoms.
 2. A process according to claim 1, wherein the alcohol or phenol has a residual water content between 10 to 1000 ppm.
 3. A process according to claim 1, wherein the alkali-metal fluoride or tetraalkylammonium fluoride has a residual water content between 0 to 990 ppm.
 4. A process according to claim 1, wherein the alkali-metal fluoride or tetraalkylammonium fluoride is added to the phosphine oxide of formula (II) at a temperature of −10° C. to 0° C., the alcohol or phenol is added, and the reaction mixture is warmed to a temperature of 20° to 60° C. until the reaction is complete.
 5. A process according to claim 1, wherein no further solvent is added to the reaction.
 6. A process according to claim 1, wherein y in the compounds of the formula (I) and (II) denotes 0, 1 or
 2. 7. A process according to claim 1, wherein y in the compounds of the formula (I) and (II) denotes
 0. 